Key result
Increasing systolic systemic pressure from 80 to 200 mmHg in vitro did not affect AS pressure gradients (mean difference 3.4±1.8 mmHg) or valve area estimates (mean difference 0.01±0.03 cm2).
Why the study?
Does systemic blood pressure directly affect pressure gradient and valve area estimates in aortic stenosis?
Does systemic blood pressure directly affect pressure gradient and valve area estimates in aortic stenosis?
Systemic blood pressure does not directly alter pressure gradients or valve area estimates in aortic stenosis when flow rate is constant, indicating that clinical variations are likely driven by flow rate changes.
Answers are grounded in this paper and cite their sources.
Systemic BP changes do not directly confound AS estimates at fixed flow; leaves open flow rate as primary clinical driver.
AIMS: Hypertension is a frequent finding in patients with aortic stenosis (AS). However, controversial data about the influence of systemic blood pressure on the quantification of AS have been published. METHODS AND RESULTS: Various models of AS (plates and biological valves) were studied in an in vitro circuit. Valve areas were calculated with the Doppler continuity equation and the Gorlin formula. Systolic systemic pressures were increased from 80 to 200 mmHg while flow rates were maintained constant. In addition, a computational fluid dynamics (CFD) model was constructed to test the effect of systemic pressures on pressure gradient and valve area estimates. When systemic pressure was raised, pressure gradients as well as valve areas did not change (mean difference 3.4 +/- 1.8 mmHg, range 0.4-6.8 mmHg; mean difference 0.01 +/- 0.03 cm(2), range -0.02 to 0.05 cm(2)). By multivariable analysis, neither valve area nor pressure gradient were independently affected by systemic pressure. In addition, CFD analysis revealed no effect of systemic pressure on pressure gradient and valve area. CONCLUSION: Our results suggest that blood pressure itself does not directly affect pressure gradients and valve area estimates in AS. Thus, when observed in vivo, these changes are most likely due to afterload-related variations of ejection fraction and, therefore, flow rate.
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Mascherbauer et al. (2008) studied Aortic stenosis. Increasing systolic systemic pressure (80 to 200 mmHg) was evaluated on Pressure gradient and valve area estimates. Increasing systolic systemic pressure from 80 to 200 mmHg in vitro did not affect AS pressure gradients (mean difference 3.4±1.8 mmHg) or valve area estimates (mean difference 0.01±0.03 cm2).
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